For centuries individuals have used key rings to hold, organize, and easily transport the keys they use on a regular basis. Some examples of prior art key rings are disclosed in the following United States Patents: U.S. Pat. No. 603,247 entitled “Key-Holder” (“'247 patent”), U.S. Pat. No. 1,462,205 entitled “Key Ring and the Like,” and Pat. No. D666,407 entitled “Key Ring.” These style key rings have the advantages of being durable and compact. However, it is often difficult to add or remove keys from these types of key rings, as the rings themselves can be very difficult to separate.
Split rings as commonly constructed have their free ends flush with the body of the ring, and when made of stiff or heavy metal it is extremely difficult to expand them sufficiently for the insertion or removal of a key with just fingers. Because of the difficulty, other aids, such as a knife-blade or other suitable article are often used to expand the split rings. Although the '247 patent issued in 1898, still, over a century later, modern day key rings are very difficult to separate in such a way so as to be able to add or remove a key.
FIG. 1 is a perspective view of a typical prior art key ring 100. As can be seen in FIG. 1, prior art key rings 100 usually consist of two concentric approximate circular supports 110, 120 that overlap one another. The lower support 110 and the upper support 120 are made as a single piece 102, often from metal which has been bent to form the two concentric approximate circular supports 110 and 120. One of the reasons that the two supports 110 and 120 are referred to as “approximate circles” and not just “circles” is because, as can be seen in FIG. 1, neither support 110, 120 is a comprised of a full 360-degrees of metal, or alternative material, on its own within a single plane. This design feature allows a user to longitudinally displace an end, e.g., 112 of either support 110 or 120 in order to add or remove a key.
Keeping keys securely in place is an obvious goal of any key ring. To keep keys in place, key rings must be able to withstand radial and orthogonal, out of plane forces that will be placed upon the key ring during ordinary use. Referring again to FIG. 1, radial forces would occur both as latitudinal forces along the x-axis 160 and longitudinal forces along the y-axis 165. In terms of orthogonal force, it is desirable for the key ring to require sufficient orthogonal force such that keys do not easily fall off of the key ring unintentionally. The orthogonal force should not, on the other hand, be so great that it is difficult to add or remove keys. The orthogonal force required to displace an end 112 of either support 110 or 120 sufficiently to facilitate the addition or removal of a key depends upon the ratio of the area moment of inertia (of the key ring cross section) to the diameter of the key ring. The area moment of inertia is proportional to the thickness of the key ring and the band width, defined as the difference between the outer and inner radii. Most key rings are designed with a sufficiently large wire gauge diameter to resist radial forces exerted on the key ring. However, the round nature of the prior art key ring as illustrated in FIG. 1 creates an equally resilient geometry resisting orthogonal forces. This results in a burdensome task for the user to overcome the orthogonal force required to add or remove keys, as described herein above.
Some inventors have addressed this long-standing problem by altering the basic shape of the key ring. By way of example, U.S. Pat. No. 803,839 entitled “Key-Ring,” disclosed carabiner-style triangular and square key rings, while U.S. Patent Application No. 2008/0087063, entitled “Key Ring Assembly,” is directed toward a key ring having a light bulb shape. While these types of key rings are easier to open than the traditional key rings described above, they are bulkier to carry, and therefore less desirable to a substantial number of consumers.